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Evaluation of the double fluorescence body test.

The double fluorescence body test for detecting Y-chromosome disjunction in human sperm cells (F-test) was evaluated. The test consisted of staining sperm cells with quinacrine and examining them by fluorescence microscopy. Semen samples were collected from 46 males (mean age 28.9 years) who were occupationally exposed to ethylene-dibromide (106934) (EDB) and also from 44 nonexposed male comparisons (mean age 34.4 years). The study was part of a NIOSH industrywide survey of the reproductive effects of EDB. Four air dried smears were prepared from each ejaculate and examined for F- bodies using the procedure. The data were analyzed by analysis of variance (ANOVA) techniques. The percentages of samples from EDB exposed workers and comparisons having no F-bodies were 52.4 and 52.3%, respectively. The percentage of samples from EDB exposed males and comparisons having one F-body was 46.3% in each case. The percentages of semen samples from exposed workers and comparisons having two F-bodies were 1.2 and 1.3%, respectively. ANOVA indicated that 39.2% of the variance in the data was due to intersubject variability within each group and 60.8% of the variance was due to intrasubject variability. The authors conclude that the F-test in its present form does not appear to be reliable enough to be used as a routine screening procedure for human ejaculates. Applying statistical power calculations to the data indicates that, in order for the F-test to be able to detect a 0.1% increase in Y- chromosome disjunction over the control value when 500 cells per slide are examined, 664 subject samples will be needed.